1992 chevrolet: timing marks..distributer..dist..the module

Customer Question

I have a 1992 chevrolet p/u with A 5.7 T.B.I. I walked into this job with the timing cover, off timing marks in the wrong place, distributer out, plugs out wires off so i put it all back together where i believe the timing marks should be, put the dist. back in and ran the wires in proper firing order the mechanic working on this said he put in two modules and it would run ( not very good and then it would quit so after putting everything back together i had no spark so i replaced the module and got spark but could not get it to run only pop through the T.B.I. where are the correct timing marks and how can i correct if the cam or crank are not right maybe 1 is off but the other is ok ?? also why is this thing eating up modules?

ok well that's where i put the marks what about the ignition modules why does it keep on going through these the mechanic working on it said here already put two in I put a third one in and got spark but still no run just backfires ?

Trust me... I work in a shop and have been working in a shop now for years. I have seen brand spanking new parts right out of the box... bad! And yes... it is possible to get a batch of bad new parts. They very well could have been made wrong at the factory. I see this quite a bit!

Yes.. it is possible that it is a bad ignition switch. THis supplies power to the ignition module. If voltage is too low, then this can burn up modules.

A back fire is simple a cylinder firing at the wrong time or at the right time but a valve is hung open for some reason and it will sound like a back fire. If its out of the exhaust, the exhaust valve in one of the cylinders was open at the time of the combustion. If it was out of the intake manifold, then it was an intake valve that was stuck open causing the noise to come from what sounded like the intake.

So to answer your question... there are lots of things that can cause a "back fire". The fuel pressure needs to be checked, the ignition timing needs to be checked. The engine mechanically needs to be checked... lifters, guides, timing chain camshaft etc.

so what do i need to check on the camshaft ? are you saying i need to tear this engine down ? by the way the modules replaced were 3 different brands 1 echlin (Napa) 1 BWD (Kragen ) and 1 Standard brand could it be the distributor ? and maybe there's too much fuel ??? Thanks for the help

To check engine engine mechanically, just hook up a vacuum gauge to the intake manifold or some sort or engine vacuum source....like any vacuum line when the engine is at idle. You want to see about 21 inches of steady vacuum. Make sure the needle on the vacuum gauge does not move around or fluctuate at all.

Next, is fuel pressure. Fuel injected vehicles are very fuel pressure sensitive and pressure must be within specifications. IF the fuel pressure is low, the fuel filter, kinked fuel pressure lines and low voltage to the fuel pump needs to be ruled out.

I get the vacuum gage but remember this engine does not run that's why i asked if i have to tear it down to inspect the components you mentioned . What would you do in my situation from the very first question ? Thanks again, oh 1 more thing where is # XXXXX on the cap or dist. ?

I will try to get you a picture of number one cylinder on the distributor.

We will have to pinpoint what the engine is missing.

Spark

Fuel

Compression

All three of these are tested when the engine is being cranked over. There are two way of checking for fuel. Fuel pressure and fuel trigger. Both are very important and must be present for the car to start. Fuel pressure is self explanatory. You just hook up the gage and see what the reading is. Fuel trigger is check with a noid light. The injector gets unplugged and the noid light gets plugged in to the injector clip. With the engine cranking over, this light must blink. This is the signal to the injectors from the computer. You can have all the fuel pressure in the world, but it wont matter if the injector is not pulsing gas into the cylinder like it should! Compression tester, spark tester, fuel pressure gage and noid light are all accessible at your local auto store. All three tests play a very important part in diagnosing a no start condition. Be extremely careful when doing these tests.

I have all of these along with compression but the engine won't run it just pops through the carb. (TBI ) now when i walked into this job the mechanic before me said he couldn't get the timing marks to line up he would line the crank up and then the cam and turn the engine over but only get compression on #1 cly. when the dot on the cam is 180 degrees out in other words getting compression when the crank dot is at 12:00 and the cam dot is @ 12:00 and when he pulled this thing apart he tells he the timing marks were@ 12:00 on the crank & 6:00 on the cam @ #1 compression stroke?? Thanks

If you want to double check it with the timing cover on, just pull out number one spark plug and turn the engine over by hand until the piston is at tdc. Pull off the distributor can and see where the rotor is pointing.

Or, what you could do it pull off the valve cover on the head that number one cylinder is on and watch the valves as the number one cylinder is at tdc. You are going to want to be sure that both valves are closed when the piston is at TDC. Or... when valve overlap occurs.

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